My DS9 has been to every signature on property (except V&A) starting at age 1. The restaurants will welcome all children whether they are dressed "properly", are behaving or not. The comments on here about only welcoming children who are "properly dressed and well-behaved" are guest comments and guest wishes for how they would like their signature dining experience to go. If you show up in park clothes, the restaurants will not turn you away. And, yes, we, too have seen children running around in signatures, which, I, too, think is inappropriate, but the restaurants have never asked any of these families to leave. The restaurants themselves seem to have a greater tolerance for misbehavior than the guests do. So, yes, all signatures are child-friendly and, while we wish all children would sit quietly through the meals, it seems that anything goes in a WDW signature. My DS once threw a fit in Citrico's as we were being seated. I promptly picked him up and left the restaurant informing the hostess we would not be eating there that evening. There was no way I was putting other guests in the restaurant through my son's tantrum.